Flame-retardant polytrimethylene terephthalate resin composition

ABSTRACT

A flame retardant polytrimethylene terephthalate resin composition, comprising:
         30 to 99 parts by weight of (A) a polytrimethylene terephthalate resin, and   1 to 70 parts by weight of at least one flame retardant selected from the group consisting of (B-1) phosphorus-containing flame retardant and (B-2) nitrogen-containing flame retardant, is disclosed. The composition has superior mechanical characteristics, chemical resistance, electrical characteristics, weatherability, heat aging resistance and hydrolysis resistance, and has superior moldability, good appearance with less warpage deformation when molded, and furthermore has superior flame retardance and does not generate highly corrosive hydrogen halide gas upon combustion.

TECHNICAL FIELD

The present invention relates to a flame retardant polytrimethyleneterephthalate resin composition. In more detail, the present inventionrelates to a flame retardant polytrimethylene terephthalate resincomposition with superior moldability, less warpage deformation and agood appearance when molded, superior flame retardance and no generationof highly corrosive hydrogen halide gas upon combustion.

BACKGROUND ART

Thermoplastic polyesters represented by polyethylene terephthalate orpolybutylene terephthalate are superior in mechanical characteristics,chemical resistance and electric characteristics, and thus are used in awide variety of fields including automotive parts andelectric/electronics parts. With the diversification of the markets inthese fields, thermoplastic polyesters are required to have higher orspecial performance and a higher quality, depending on theirapplications. Polytrimethylene terephthalate resin, among otherpolyester resins, is superior in mechanical characteristics,weatherability, heat aging resistance and hydrolysis resistance. It alsohas superior properties such that when reinforced with inorganicfillers, the appearance of the molding is not impaired and warpage ofthe molding hardly occurs. Its uses can thus be extended to a widevariety of fields.

For the application with electric/electronics parts, which is one of thefields where the application of polytrimethylene terephthalate resin isexpected to extend, a level of flame retardance based on the UL-94standard by UNDERWRITERS LABORATORIES is required.

To satisfy this requirement, compositions containing halogen type flameretardants have conventionally been studied. For example, JP-A-50-49361proposes a resin composition consisting of polypropylene terephthalateor polybutylene terephthalate, decabromodiphenyl ether, antimonytrioxide and asbestos. U.S. Pat. No. 4,131,594 proposes a resincomposition consisting of polytrimethylene terephthalate and a graftcopolymer, a halogen type flame retardant, such as a polycarbonateoligomer of decabromobiphenyl ether or tetrabromobisphenol A, antimonyoxide and glass fiber. However, such a halogen type flame retardantgenerates corrosive hydrogen halide upon combustion and also issuspected of discharging toxic substances such as dioxin. There is thusa movement to control the use of plastic products containing a halogentype flame retardant.

In this movement, JP-A-2000-169681, for example, proposes a flameretardant resin composition consisting of polytrimethylene terephthalateand red phosphorus. However, the use of this composition is limitedbecause it has a red color and possibly generates phosphine gas duringprocessing. Further, EP 0955338, EP 0955333 and JP 310284 propose resincompositions consisting of polybutylene terephthalate, melaminecyanurate, ammonium polyphosphate or melamine polyphosphate, phosphateester and glass fiber. These compositions, however, have large warpagedeformation and a poor appearance when molded, and thus cannotsufficiently satisfy the market's needs.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a polytetramethyleneterephthalate resin composition with superior mechanicalcharacteristics, chemical resistance, electric characteristics,

An object of the present invention is to provide a polytrimethyleneterephthalate resin composition with superior mechanicalcharacteristics, chemical resistance, electric characteristics,weatherability, heat aging resistance and hydrolysis resistance, as wellas superior moldability, a good appearance with less warpage deformationwhen molded, superior flame retardance and no generation of highlycorrosive hydrogen halide gas upon combustion, that sufficientlysatisfies the market's requirements. weatherability, heat agingresistance and hydrolysis resistance, as well as superior moldability, agood appearance with less warpage deformation when molded, superiorflame retardance and no generation of highly corrosive hydrogen halidegas upon combustion, that sufficiently satisfies the market'srequirements.

The inventors found that a flame retardant resin composition withsuperior moldability, less warpage deformation and a good appearancewhen molded, superior flame retardance and no generation of highlycorrosive hydrogen halide gas upon combustion, can be provided by aresin composition comprising a (A) polytrimethylene terephthalate resinand at least one flame retardant selected from a group consisting of(B-1) phosphorus-containing flame retardants and (B-2)nitrogen-containing flame retardants, and thus accomplished the presentinvention.

The aspects of the present invention thus relate to the following:

-   (1) A flame retardant polytrimethylene terephthalate resin    composition, comprising:

30 to 99 parts by weight of (A) a polytrimethylene terephthalate resin,and

1 to 70 parts by weight of at least one flame retardant selected fromthe group consisting of (B-1) phosphorus-containing flame retardants and(B-2) nitrogen-containing flame retardants.

-   (2) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (1), wherein said (B-1)    phosphorus-containing flame retardants are phosphate ester compounds    or condensed phosphate ester compounds.-   (3) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (2), wherein said (B-1)    phosphorus-containing compounds are condensed phosphate ester    compounds represented by general formula (1):

-    or by general formula (2):

-    wherein, Ar¹ to Ar⁴ and Ar⁵ to Ar⁸ may be the same or different and    represent a phenyl group or a phenyl group substituted with an    organic residual group(s) not containing halogen; and n1 and n2    represent number average degrees of polymerization.-   (4) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (1), wherein said (B-1)    phosphorus-containing flame retardants are phosphazene compounds    comprising a repeating unit represented by general formula (3):

-    wherein Rs may be the same or different, and represent an alkyl    group, aryl group, alkoxy group, aryloxy group, alkylamino group,    arylamino group, hydroxyl group or amino group.-   (5) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (4), wherein said (B-1)    phosphorus-containing compounds are linear phosphazene compounds    represented by general formula (4) and/or cyclic phosphazene    compounds represented by general formula (5):

-    (in general formulae (4) and (5), m1 is an integer of 3 to 1,000;    m2 is an integer of 3 to 25; R¹ and R² may be the same or different,    and represent a phenyl group substituted with at least one group    selected from the group consisting of alkyl groups and allyl groups    having 1 to 6 carbon atoms, or a non-substituted phenyl group; X is    —N═P(OR¹)₃ group or —N═P(O)OR¹ group; and Y is —P(OR¹)₄ group or    —P(O)(OR¹)₂ group).-   (6) The flame retardant polytrimethylene terephthalate resin    composition in accordance with any one of (1) to (5), wherein said    (B-2) nitrogen-containing flame retardants are melamine type    compounds or salts of a melamine type compound and cyanuric acid or    isocyanuric acid.-   (7) The flame retardant polytrimethylene terephthalate resin    composition in accordance with any one of (1) to (5), wherein said    (B-2) nitrogen-containing flame retardants are selected from salts    of phosphoric acid or a polyphosphoric acid and ammonia or melamine    type compounds.-   (8) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (7), wherein said (B-2)    nitrogen-containing flame retardants are melamine polyphosphates.-   (9) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (1), wherein said flame retardant    comprises at least one of said (B-1) phosphorus-containing flame    retardants and at least one of said (B-2) nitrogen-containing flame    retardants.-   (10) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (9), comprising:

30 to 99 parts by weight of said (A) polytrimethylene terephthalateresin, and

1 to 70 parts by weight of flame retardants, wherein said flameretardants consist of 3 to 75 parts by weight of at least one (B-1)phosphorus-containing flame retardant and 25 to 97 parts by weight of atleast one (B-2) nitrogen-containing flame retardant, with respect to thetotal amount of said flame retardants.

-   (11) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (10), comprising:

30 to 98 parts by weight of said (A) polytrimethylene terephthalateresin,

1 to 25 parts by weight of at least one (B-1) phosphorus-containingflame retardant, and

1 to 45 parts by weight of at least one (B-2) nitrogen-containing flameretardant.

-   (12) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (1), further comprising 5 to 150    parts by weight of (C) an inorganic filler with respect to the total    of 100 parts by weight of 30 to 99 parts by weight of said (A)    polytrimethylene terephthalate resin and 1 to 70 parts by weight of    said (B-1) phosphorus-containing flame retardant and/or said (B-2)    nitrogen-containing flame retardant.-   (13) The flame retardant polytrimethylene terephthalate resin    composition in accordance with (12), wherein said (C) inorganic    filler is glass fiber.-   (14) A molding comprising the flame retardant polytrimethylene    terephthalate resin composition in accordance with any one of (1) to    (13).-   (15) The molding in accordance with (14), which is an injection    molded product.

BEST MODE FOR CARRYING OUT THE INVENTION

A flame retardant polytrimethylene terephthalate resin composition ofthe present invention will be described below in detail.

The polytrimethylene terephthalate (hereinafter abbreviated as “PTT”) inthe present invention is a polyester polymer using terephthalic acid asan acid component and trimethylene glycol as a glycol component.

Said trimethylene glycol is selected from 1,3-propanediol,1,2-propanediol, 1,1-propanediol, 2,2-propanediol and a mixture thereof,and 1,3-propanediol is particularly preferable in view of thecrystallization rate.

Further, the PTT in the present invention includes those obtained bycopolymerization using other acid components than terephthalic acid,including an aromatic dicarboxylic acid such as phthalic acid,isophthalic acid, 2,6-naphthalene-dicarboxylic acid, diphenylcarboxylicacid, diphenylether-dicarboxylic acid, diphenoxyethane-dicarboxylicacid, diphenylmethane-dicarboxylic acid, diphenylketone-dicarboxylicacid and diphenylsulfone-dicarboxylic acid; an aliphatic dicarboxylicacid such as succinic acid, adipic acid and sebacic acid; an alicyclicdicarboxylic acid such as cyclohexane-dicarboxylic acid; anoxydicarboxylic acid such as ε-oxycapronic acid, hydroxybenzoic acid andhydroxyethoxybenzoic acid; and other glycol components than trimethyleneglycol such as ethylene glycol, tetramethylene glycol, pentamethyleneglycol, hexamethylene glycol, octamethylene glycol, neopentyl glycol,cyclohexane-dimethanol, xylylene glycol, diethylene glycol,polyoxyalkylene glycol and hydroquinone, as long as the object of thepresent invention is met.

In said copolymerization, the amount of the acid component(s) other thanterephthalic acid and/or the glycol component(s) other than trimethyleneglycol are not particularly limited as long as the object of the presentinvention is not impaired, but are usually preferable to be 20% by moleor less of the total acid components and/or 20% by mole or less of thetotal glycol components, respectively.

Further, a branching component, for example, a tri- or tetra-functionalacid capable of forming an ester, such as tricarballylic acid, trimesicacid and trimellitic acid or a tri- or tetra-functional alcohol capableof forming an ester such as glycerin, trimethylolpropane andpentaerythritol may be copolymerized to the above-described polyestercomponents. In this case, the amount of said branching component is 1.0%by mole or less, preferably 0.5% by mole or less and more preferably0.3% by mole or less, of the total acid components or the total glycolcomponents. Furthermore, two or more kinds of these copolymer componentsmay be used in combination to obtain the PTT.

The method for producing the PTT used in the present invention is notparticularly limited, and can be, for example, in accordance with themethods described in JP-A-51-140992, JP-A-5-262862 and JP-A-8-311177.

One example is a method comprising reacting terephthalic acid or anester forming derivative thereof (for example, a lower alkyl ester suchas dimethylester and monomethylester) with trimethylene glycol or anester forming derivative thereof under heating at a suitable temperaturefor a suitable period of time in the presence of a catalyst, and furtherpolycondensing the resultant glycol ester of terephthalic acid at asuitable temperature for a suitable period of time in the presence of acatalyst to have a desired degree of polymerization.

The polymerization method is also not particularly limited and includesmelt polymerization, interfacial polymerization, solutionpolymerization, mass polymerization, solid phase polymerization and acombined method thereof.

In the PTT used in the present invention, various additives may becopolymerized or mixed, if necessary, such as a heat stabilizer, adefoaming agent, a color adjustment agent, an antioxidant, a UVabsorber, an infrared ray absorber, a nucleating agent, a fluorescentwhitener and a delustering agent.

The limiting viscosity [η] of the PTT in the present invention is notparticularly limited, but is preferably 0.50 or more, more preferably0.60 or more and most preferably 0.70 or more, in view of mechanicalcharacteristics and fatigue characteristics.

The limiting viscosity [η] can be determined using an Ostwald'sviscometer at 35° C., by dissolving a resin in o-chlorophenol so thatthe solute (PTT component) concentration becomes 1.00 g/dl, measuringthe specific viscosity, ηsp of the supernatant liquid afterprecipitating insoluble solids (such as inorganic filler), andcalculating by the following equation:[η]=0.713×(ηsp/C)+0.1086

C=1.00 g/dl

Next, (B-1) a phosphorus-containing flame retardant in the presentinvention includes phosphate ester compounds, condensed phosphate estercompounds, phosphazene compounds, phosphine compounds and phosphineoxidecompounds.

A phosphate ester compound which can be used in the present inventionincludes trimethyl phosphate, triethyl phosphate, tributyl phosphate,trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylylphosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate,tolyldixylyl phosphate, tris(nonylphenyl) phosphate,(2-ethylhexyl)diphenyl phosphate, resorcinoldiphenyl phosphate andhydroquinonediphenyl phosphate. Among them, aromatic phosphate estercompounds such as triphenyl phosphate, tricresyl phosphate and trixylylphosphate are preferable.

A condensed phosphate ester compound includes resorcinol-bis(diphenylphosphate), hydroquinone-bis(diphenyl phosphate),bisphenol-A-bis(diphenyl phosphate), bisphenol-S-bis(diphenylphosphate), resorcinol-bis(dixylyl phosphate), hydroquinone-bis(dixylylphosphate), bisphenol-A-bis(dixylenyl phosphate), resorcinol-bis(ditolylphosphate) and bisphenol-A-bis(ditolyl phosphate).

Among these condensed phosphate ester compounds, particularly preferablecompounds are those represented by general formula (1):

or by general formula (2):

(in the general formulae (1) and (2), Ar¹ to Ar⁴ and Ar⁵ to Ar⁸ may bethe same or different, and represent a phenyl group or a phenyl groupsubstituted with an organic residue(s) not containing halogen; n1 and n2represent number average degrees of polymerization). As Ar¹ to Ar⁸, aphenyl group, tolyl group and xylyl group are more preferably used andresorcinolbis(diphenyl phosphate), resorcinolbis(dixylyl phosphate),bisphenol-A-bis(diphenyl phosphate) and bisphenol-A-bis(dixylenylphosphate) (all correspond to those when n1 and n2 are 1) areparticularly preferable. The condensed phosphate ester is obtainedindustrially as a mixture of compounds having different degrees ofpolymerization, and each of n1 and n2 representing the number averagedegree of polymerization is preferably 0.5 to 5.

Further, as (B-1) a phosphorus-containing flame retardant in the presentinvention, a phosphazene compound having a repeating unit represented bygeneral formula (3):

can be used. Here, R may be a functional group having any chemicalstructure except for a halogen-containing group. Specifically, Rincludes an alkyl group, an aryl group, an alkoxy group, an aryloxygroup, an alkylamino group, an arylamino group, an hydroxyl group and anamino group. These functional groups can be used alone or in combinationof two or more. The repeating unit represented by the above formula maybe bonded in cyclic or linear form. A phosphazene compound consisting ofthe repeating unit represented by the above formula may be an oligomeror a polymer. For example, a phosphazene compound includes thosedescribed in James E. Mark, Harry R. Allcock, Robert West, “InorganicPolymers” (Prentice-Hall International, Inc., 1992), p. 61–140.

More preferable phosphazene compounds include a linear and a cyclicphosphazene compound represented by the following general formula (4) or(5) and the same phosphazene compound crosslinked with a phenylenegroup, a biphenylene group or the like:

(wherein, m1 is an integer of 3 to 1,000; two R¹s may be the same ordifferent, and represent a phenyl group substituted with at least onegroup selected from the group consisting of alkyl groups and allylgroups having 1 to 6 carbon atoms, or a non-substituted phenyl group; Xis a —N═P(OR¹)₃ group or —N(O)OR¹ group; and Y is a —P(OR¹)₄ group or a—P(O)(OR¹)₂ group);

(wherein, m2 is an integer of 3 to 25; and R¹ is the same as definedabove).

A phosphazene compound not containing a halogen atom can be used aloneor in combination of two or more. A mixture of a cyclic phosphazenecompound and a linear phosphazene compound may also be used.

Specific examples of a linear phosphazene compound represented by theabove general formula (4) and a cyclic phosphazene compound representedby the above general formula (5) include, for example, phosphazenecompounds of a mixture of cyclic and linear chlorophosphazene compounds,such as hexachlorocyclotriphosphazene andoctachlorocyclotetraphosphazene obtained by reacting ammonium chloridewith phosphorus pentachloride at about 120 to 130° C. and substitutedwith a phenoxy group(s) and/or an alkoxy group(s); and cyclicphosphazene compounds such as hexaphenoxycyclotriphosphazene,octaphenoxycyclotetraphosphazene, decaphenoxycyclopentaphosphazene,hexaalkoxycyclotriphosphazene, octaalkoxycyclotetraphosphazene anddecaalkoxycyclopentaphosphazene obtained by isolating a single substancesuch as hexachlorocyclotriphosphazene, octachlorocyclotetraphosphazeneand decachlorocyclopentaphosphazene from the above described mixture ofchlorophosphazene compounds, then substituting with a phenoxy groupsand/or an alkoxy group(s). In addition, linear phosphazene compounds arealso included, which are obtained by ring opening polymerization ofhexachlorocyclotriphosphazene under heating (220 to 250° C.) to preparedichlorophosphazene and then substituting with a phenoxy groups and/oran alkoxy group(s).

Among these, linear phosphazene compounds represented by theabove-described general formula (4) wherein m1 is an integer of 3 to 25and cyclic phosphazene compounds represented by the above-describedgeneral formula (5) wherein m2 is an integer of 3 to 8, are particularlypreferable.

The purity of the phosphazene compound depends on the raw materials,manufacturing method and manufacturing conditions thereof, but usuallyis about 98 to 99%. The purity of the phosphazene compound which can beused in the present invention is not particularly limited, but is 90% ormore and, preferably, 95% or more. A purity in this range makes itpossible to pulverize the compound simply and in a short time, thusproviding a powder of phosphazene compound having a better powder state.

A phosphine compound which can be used in the present invention includestrilaurylphosphine, triphenylphosphine and tritolylphosphine.

A phosphineoxide compound includes triphenylphosphineoxide andtritolylphosphineoxide.

These phosphorus-containing flame retardants may be used alone or incombination of two or more.

Component (B-2), a nitrogen-containing flame retardant in the presentinvention, includes melamine type compounds, salts of cyanuric acid orisocyanuric acid and a melamine compound and a salt of phosphoric acidor polyphosphoric acid and a melamine compound.

A melamine type compound as used herein means melamine, a melaminederivative, a compound having a structure similar to melamine and acondensed compound of melamine, and specifically includes compoundshaving a triazine structure such as melamine, ammelide, ammeline,formoguanamine, guanylmelamine, cyanomelamine, benzoguanamine,acetoguanamine, succinoguanamine, melam, melem, methone and mellon;sulfate salts thereof; and a melamine resin. Melamine and melem areparticularly preferable.

Cyanuric acid or isocyanuric acid is a compound represented by generalformula (6):

or general formula (7):

(wherein, R⁴, R⁵ and R⁶ may be the same or different, and are a hydrogenatom or an alkyl group) (hereinafter, these compounds are calledcyanuric acids or isocyanuric acids). A specific example of a compoundrepresented by general formula (6) includes cyanuric acid, trimethylcyanurate, triethyl cyanurate, tri(n-propyl) cyanurate, methyl cyanurateand diethyl cyanurate, and a specific example of a compound representedby general formula (7) includes isocyanuric acid, trimethylisocyanurate, triethyl isocyanurate, tri(n-propyl) isocyanurate, diethylisocyanurate and methyl isocyanurate.

A salt of cyanuric acid or isocyanuric acid and a melamine type compoundwhich can be used in the present invention is an equimolar reactionproduct of the above-described cyanuric acid or isocyanuric acid with amelamine compound, which can be obtained as a white solid, for example,by mixing an aqueous solution of cyanuric acid and an aqueous solutionof melamine, then reacting them at 90 to 100° C. under stirring followedby filtering the resulting precipitate. Some of the amino or hydroxylgroups in melamine cyanurate may be-substituted with other substituents.Among these salts of cyanuric acid or isocyanuric acid and a melaminecompound, melamine cyanurate is most preferable.

Further, a salt of phosphoric acid or polyphosphoric acid and ammonia ora melamine compound, which can be used in the present invention as anitrogen-containing flame retardant, includes ammonium phosphate,ammonium polyphosphate, melamine phosphate, melamine pyrophosphate andmelamine polyphosphate.

For example, an industrially available ammonium polyphosphate includes“Taien S” (trade mark of a product from Taihei Chem. Ind. Co., Ltd.),obtained by treating ammonium polyphosphate with a melamine resin tomake it hardly dissolvable in water, “Sumisafe P” and “Sumisafe PM”(trade marks of products from Sumitomo Chem. Ind. Co., Ltd.), “Exolit462” (trade mark of a product from Hoechst AG) and “AMGARD MC” (trademark of a product from Albright & Wilson) and the like.

Furthermore, “Exolit VP IFR-23” (trade mark of a product from HoechstAG), “SPINFLAM MF80/PP”, “SPINFLAM MF82/PP” and “SPINFLAM MF82/PS”(trade marks of products from Montecatini), which have been improved inflame retardation effect by using other auxiliary components incombination with ammonium polyphosphate, may be included.

Furthermore, a phosphoric acid comprising melamine phosphatespecifically includes: orthophosphoric acid, phosphorous acid,hypophosphorous acid, metaphosphoric acid, pyrophosphoric acid,triphosphoric acid, and tetraphosphoric acid, and an adduct usingorthophosphoric acid which is particularly preferable.

A polyphosphoric acid comprising melamine polyphosphate is generallycalled a condensed phosphoric acid, and includes a linear polyphosphoricacid and a cyclic polymetaphosphoric acid. Although the degree ofcondensation of these polyphosphoric acids is usually 3 to 50, thisparameter is not particularly limited in the present invention.

A melamine polyphosphate which can be used in the present inventionmeans a melamine adduct formed from substantially equimolar melamine andthe above-described phosphoric acid, pyrophosphoric acid andpolyphosphoric acid, and a part of the functional groups may be in afree state. Such melamine adduct is a powder obtained, for example, bythoroughly mixing a mixture of melamine and the above-describedphosphoric acid as a slurry in water, then forming fine particles of theadduct of both components, followed by filtering the slurry, washing anddrying, and then crushing the resulting solid. It is preferable to use acrushed powder of the melamine adduct having a particle diameter of 100μm or less and preferably 50 μm or less. The use of the powder with aparticle diameter of 0.5 to 20 μm is particularly preferable in view ofnot only the expression of high flame retardance but also the remarkablyhigh strength of the molded articles.

These nitrogen-containing flame retardants may be used alone or incombination of two or more.

The content of each component in a flame retardant polytrimethyleneterephthalate resin composition of the present invention is preferablyin a range. of 30 to 99 parts by weight for (A) a polytrimethyleneterephthalate resin and 1 to 70 parts by weight for at least one flameretardant selected from a group consisting of (B-1)phosphorus-containing flame retardants and (B-2) nitrogen-containingflame retardants. More preferable contents are 40 to 96 parts by weightfor (A) a polytrimethylene terephthalate resin and 4 to 60 parts byweight for at least one flame retardant selected from a group consistingof (B-1) phosphorus-containing flame retardants and (B-2)nitrogen-containing flame retardants. If the content of (A) thepolytrimethylene terephthalate resin is lower than 30 parts by weight,moldability and mechanical properties of molded articles will beimpaired. If the content of at least one flame retardant selected from agroup consisting of (B-1) phosphorus-containing flame retardants and(B-2) nitrogen-containing flame retardants is lower than 1 part byweight, the flame retardation effect will be insufficient. On the otherhand, if the content is over 70 parts by weight, problems such as thegeneration of decomposition gas upon kneading and the adhesion ofcontaminants to a metal mold upon molding will occur, and further aremarkable lowering in mechanical properties or poor appearance ofmolded articles may occur.

Furthermore, in a flame retardant polytrimethylene terephthalate resincomposition of the present invention, by using at least one (B-1)phosphorus-containing flame retardant and at least one (B-2)nitrogen-containing flame retardant together, as flame retardants, theflame retardation effect can be enhanced. In this case, a preferablecontent of each flame retardant with respect to the total amount of theflame retardants is 3 to 75 parts by weight for (B-1) aphosphorus-containing flame retardant(s) and 25 to 97 parts by weightfor (B-2) a nitrogen-containing flame retardant(s). A further preferableratio is 30 to 98 parts by weight for (A) polytrimethylene terephthalateresin, 1 to 25 parts by weight for at least one (B-1)phosphorus-containing flame retardant and 1 to 45 parts by weight for atleast one (B-2) nitrogen-containing flame retardant.

Next, (C) an inorganic filler which can be used in the present inventionwill be described.

As an inorganic filler in the present invention, at least one inorganicfiller selected from a group consisting of fibrous inorganic fillers,powdery inorganic fillers and plate-like inorganic fillers can be used,depending on the objective.

Fibrous inorganic fillers include glass fiber, carbon fiber, silicafiber, silica-alumina fiber, zirconia fiber, boron nitride fiber,silicone nitride fiber, boron fiber, potassium titanate whisker,wollastonite, and furthermore fiber-like substances of metals such asstainless steel, aluminum, titanium, copper and brass. An organicfibrous substance with a high melting point, such as a polyamide,fluorocarbon resin and acrylic resin may be used in combination with aninorganic filler(s).

Here, the average fiber length (hereinafter, also referred to as “L”),average fiber diameter (hereinafter, also referred to as “D”) and aspectratio (hereinafter, also referred to as “L/D”) of the fibrous inorganicfiller are not specifically limited. However, the average fiber lengthis preferably 50 μm or more in view of mechanical characteristics andfatigue characteristics, the average fiber diameter is preferably 5 μmor more and the aspect ratio is preferably 10 or more.

Further, with respect to carbon fiber, a carbon fiber having an averagefiber length (L) of 100 to 750 μm, an average fiber diameter (D) of 3 to30 μm and an aspect ratio (L/D) of 10 to 100 is preferably used.Furthermore, for wollastonite, a wollastonite having an average fiberlength of 10 to 500 μm, an average fiber diameter of 3 to 30 μm and anaspect ratio (L/D) of 3 to 100 is preferably used.

Powdery inorganic fillers include carbon black, silica, quartz powder,glass beads, glass powder, silicates such as calcium silicate, aluminumsilicate, kaolin, clay and diatomaceous earth; metal oxides such as ironoxide, titanium oxide, zinc oxide and alumina; metal carbonates such ascalcium carbonate and magnesium carbonate; metal sulfates such ascalcium sulfate and barium sulfate; silicone carbide; silicone nitride;boron nitride; and various metal powders. In this connection, withrespect to talc, mica, kaolin, calcium carbonate and potassium titanate,those having an average particle diameter of 0.1 to 100 μm are mostpreferably used.

Plate-like inorganic fillers include talc, mica, glass flake, variousmetal foils and the like.

As an inorganic filler in the present invention, glass fiber is mostpreferably used in view of mechanical characteristics and fatiguecharacteristics. The glass fiber can be any glass fiber, as long as itcan be usually compounded in a polyester resin, and its type and thelike are not particularly limited.

Further, an inorganic filler may be used alone or in combination of twoor more. The use of a glass fiber and an inorganic filler other thanglass fiber together, in particular, the use of a glass fiber and agranular and/or plate-like inorganic filler together is preferable inview of providing mechanical strength, dimensional accuracy anddesirable electrical properties.

The amount of (C) an inorganic filler to be blended is preferably in arange of 5 to 150 parts by weight with respect to the total of 100 partsby weight of 30 to 99 parts by weight of (A) a polytrimethyleneterephthalate resin and 1 to 30 parts by weight of (B-1) aphosphorus-containing flame retardant(s) and/or (B-1) anitrogen-containing flame retardant(s). More preferably, the amount ofan (D) inorganic reinforcing filler is in a range of 10 to 120 parts byweight.

These inorganic fillers are preferably used, in particular, after beingsubjected to a surface treatment. The surface treatment is performedusing a known coupling agent or a film-forming agent. The coupling agentpreferably used includes a silane-based coupling agent and atitanium-based coupling agent. As a film-forming agent, an epoxypolymer, an urethane polymer, an acrylic acid-based polymer and amixture thereof are preferably used.

To a flame retardant polytrimethylene terephthalate resin composition ofthe present invention, other components may be added in addition to theabove-described polytrimethylene terephthalate resin, a flame retardantand an inorganic filler, if necessary, depending on various applicationsand the object.

By further blending a nucleating agent in a resin composition of thepresent invention, a composition with higher mechanical strength can beobtained. The nucleating agent may be a generally used known one, andmay be of organic type or inorganic type.

By further blending a moldability improver in a resin composition of thepresent invention, a flame retardant resin composition with bettermoldability and better appearance when molded can be obtained. Themoldability improver includes phosphate esters, phosphite esters, higherfatty acids, metal salts of higher fatty acids, esters of higheralcohols and higher fatty acids, higher fatty acid esters such as estersbetween polyhydric alcohols and higher fatty acids, higher fatty acidamide compounds, polyalkylene glycols or terminal-modified derivativesthereof, low molecular weight polyethylenes or oxidized low molecularweight polyethylenes, substituted benzylidenesorbitols, polysiloxanesand caprolactones. Particularly preferable moldability improvers arehigher fatty acids, metal salts of higher fatty acids and higher fattyacid esters.

Further, to a resin composition of the present invention, additivesusually used, such as a UV absorber, a heat stabilizer, an antioxidant,a plasticizer, a coloring agent and an impact strength improver can alsobe added, as long as the object of the present invention is met.

To a resin composition of the present invention, a thermoplastic resinmay also be added as long as the object of the present invention is met.The thermoplastic resin includes polycarbonate, polyethyleneterephthalate, polybutylene terephthalate and polystyrene type resin(rubber-reinforced polystyrene and an acrylonitrile-butadiene-styreneresin).

The method for producing a flame retardant polytrimethyleneterephthalate resin composition of the present invention is notparticularly limited, but includes a method of melt-kneading a mixtureof a polytrimethylene terephthalate resin, a flame retardant(s) and, ifnecessary, an inorganic filler(s) and an additive(s), using a knownmelt-kneader, such as a single-screw or multi-screw extruder, kneader,mixing roll and Banbury mixer at a temperature of 200 to 400° C. Inparticular, melt-kneading with an extruder is simple and thuspreferable.

A flame retardant polytrimethylene terephthalate resin composition ofthe present invention, as compared to conventional resin compositions,is superior in mechanical characteristics, chemical resistance,electrical characteristics, weatherability, heat aging resistance andhydrolysis resistance, and has superior moldability, good appearance andless warpage deformation when molded. Furthermore, it has superior flameretardance and does not generate highly corrosive hydrogen halide gasupon combustion. The composition, therefore, can be molded into variousmoldings, such as electric/electronic parts including a connector, coilbobbin, breaker, holder, plug and switch; automotive parts; andmechanical and structural parts by known molding methods, such asinjection molding, extrusion molding, compression molding and blowmolding, in particular, by injection molding.

EXAMPLES

The present invention will be described in more detail by way ofExamples, however, the present invention is not limited by theseExamples. The molding method and evaluation methods for variousproperties of the samples described in the Examples and ComparativeExamples are as follows.

(Method for Molding Sample(s))

Samples were molded using an injection molding machine, “PS40E” fromNissei Plastic Co., Ltd., under conditions of a mold temperature of 95°C. and a cylinder temperature of 250° C. to obtain the moldings.

(Evaluation Methods for Various Characteristics)

(1) Limiting Viscosity [η] (Polytrimethylene Terephthalate ResinComposition)

A value of [η] (for a molding) was determined using the Ostwald'sviscometer at 35° C. by dissolving the resin in o-chlorophenol with apurity of 98% or more so that the solute/solution concentration became1.00 g/dl, followed by measuring the specific viscosity ηsp of thesupernatant liquid therefrom and calculating in accordance with thefollowing equation:[η]=0.713×(ηsp/C)+0.1086

(providing C=1.00 g/dl).

(2) Flame Retardance

Measurement was performed using a test piece with a thickness of 1/16inch, in accordance with UL-94V standard as specified by UNDERWRITERSLABORATORIES, U.S.A.

(3) Flexural Modulus (GPa)

It was measured in accordance with ASTM D790.

(4) Flexural Strength (MPa)

It was measured in accordance with ASTM D790.

(5) Warpage Deformation

An injection molded flat plate obtained by using a metal mold, with athickness of 3 mm and a side length of 130 mm, was placed on ahorizontal plane to measure the maximum gap width between the plate andthe horizontal plane.

(6) Appearance of Molding

According to JIS-K7150, a value of Gs 60° C. was measured using a handygloss meter “IG320” from Horiba Ltd. A sample with a measured value of70 or more was evaluated as o, whereas a sample with a measured value ofless than 70 was evaluated as x.

Materials used in the Examples and the Comparative Examples are ShownBelow

Resins

-   a-1: Polytrimethylene terephthalate resin, [η]=0.90 (PTT-1)-   a-2: Polytrimethylene terephthalate resin, [η]=1.00 (PTT-2)-   a-3: Polybutylene terephthalate resin (PBT), “Duranex 2002” (trade    mark of a product from Polyplastics Co., Ltd.)-   a-4: Polyethylene terephthalate resin (PET), “NEH-205” (trade mark    of a product from Unitica Ltd.)    (B-1) Phosphorus-Containing Flame Retardants-   b-1: Condensed phosphate ester compound:

-   b-2: Condensed phosphate ester compound:

-   b-3: Phosphazene compound; phenoxyphosphazene represented by the    following formula (10), “P-3800” (trade name of a product from    Nippon Soda Co., Ltd.), a mixture of a compound with n=1 and a    compound with n=2 (wherein, Ar represents a benzene ring).

(B-1) Nitrogen-Containing Flame Retardants

-   b-4: melamine cyanurate (average particle diameter of 1.3 μm)-   b-5: melem (average particle diameter of 1.8 μm)-   b-6: melamine polyphosphate (average particle diameter of 3 μm)    (C) Inorganic Filler-   c: glass fiber: “FT153” from Asahi Fiber Glass Co., Ltd.

Examples 1 to 9 and Comparative Examples 1 to 5

(A) a polytrimethylene terephthalate resin, a polybutylene terephthalateresin and a polyethylene terephthalate resin, (B-1) aphosphorus-containing flame retardant(s), (C) a nitrogen-containingflame retardant(s) and (D) an inorganic filler(s) are pre-mixed in theblend ratios shown in Table 1 with a blender, followed by melt kneadingwith a twin-screw extruder (“TEM35” from Toshiba Machinery CO., Ltd.)under the conditions of a predetermined cylinder temperature of 250° C.and a screw revolving speed of 200 rpm, taken out in the form of astrand and pelletized with a cutter to obtain pellets. Variousproperties of the pellets thus obtained were examined by theabove-described measurement methods. The results are shown in Table 1.In Comparative Example 5 using polyethylene terephthalate (PET),problems in moldability, such as poor mold release occurred in theinjection molding stage, which made the evaluation of the propertiesimpossible.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Example 7 Example 8 Example 9 Composition (a-1) PTT Resin-1 40 45 35 40(parts by (a-2) PTT Resin-2 50 55 35 40 65 weight) (a-3) PBT Resin (a-4)PET Resin (b-1) Condensed 20 15 10 5 15 phosphate ester (b-2) Condensed5 phosphate ester (b-3) Phosphazene 15 15 compound (b-4) Melaminecyanurate 20 30 (b-5) Melem 15 (b-6) Melamine 30 15 25 20 polyphosphate(c-1) Glass fiber 30 30 30 30 30 30 30 30 0 Evaluation Flexural Gpa 7.77.8 13.0 7.8 8.3 8.1 11.5 11.9 3.8 modulus Flexural MPa 170 175 120 130150 135 175 180 110 strength Warpage mm 2 2 1 1 1 1 1 1 2 deformationAppearance Visual ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ of molding Examination Flame UL-94V-2 V-2 V-1 V-0 V-0 V-0 V-0 V-0 V-2 retardance Comparative ComparativeComparative Comparative Comparative Example 1 Example 2 Example 3Example 4 Example 5 Composition (a-1) PTT Resin-1 70 (parts by (a-2) PTTResin-2 weight) (a-3) PBT Resin 50 40 35 (a-4) PET Resin 35 (b-1)Condensed phosphate ester 20 15 15 (b-2) Condensed phosphate ester (b-3)Phosphazene compound (b-4) Melamine cyanurate 20 20 (b-5) Melem (b-6)Polyphosphoric acid- 30 melamine adduct (c-1) Glass fiber 30 30 30 30 30Evaluation Flexural Gpa 9.1 7.5 10.5 7.8 Not moldable modulus FlexuralMPa 206 175 120 120 Not moldable strength Warpage mm 2 6 5 6 Notmoldable deformation Appearance Visual Examination ◯ X X X Not moldableof molding Flame UL-94 V-2 out V-2 out V-2 out V-2 out Not moldableretardance

INDUSTRIAL APPLICABILITY

A flame retardant polytrimethylene terephthalate resin composition ofthe present invention has superior mechanical characteristics, chemicalresistance, electric characteristics, weatherability, heat agingresistance and hydrolysis resistance, as well as superior moldabilityand good appearance with less warpage deformation when molded, andfurthermore has superior flame retardance and does not generate highlycorrosive hydrogen halide gas upon combustion. Thus, the composition canbe suitably used for electric/electronic parts such as a connector, acoil bobbin, a breaker, a holder, a plug and a switch; automotive parts;and mechanical and structural parts; and the like.

1. A flame retardant polytrimethylene terephthalate resin composition,comprising: 30 to 99 parts by weight of (A) a polytrimethyleneterephthalate resin having a limiting viscosity [η] of 0.70 or more, and1 to 70 parts by weight of flame retardants comprising at least one of(B-1) phosphorus-containing flame retardants which are phosphate estercompounds or condensed phosphate ester compounds and at least one of(B-2) nitrogen-containing flame retardants selected from salts of i)phosphoric acid or a polyphosphoric acid with ii) ammonia or melaminecompounds.
 2. The flame retardant polytrimethylene terephthalate resincomposition in accordance with claim 1, wherein said (B-1)phosphorus-containing compounds are condensed phosphate ester compoundsrepresented by general formula (1):

or by general formula (2):

wherein Ar¹ to Ar⁴ and Ar⁵ to Ar⁸ may be the same or different andrepresent a phenyl group or a phenyl group substituted with an organicresidual group(s) not containing halogen; and n1 and n2 represent numberaverage degrees of polymerization.
 3. The flame retardantpolytrimethylene terephthalate resin composition in accordance withclaim 1, wherein said (B-2) nitrogen-containing flame retardants aremelamine polyphosphates.
 4. The flame retardant polytrimethyleneterephthalate resin composition in accordance with claim 1, comprising:30 to 99 parts by weight of said (A) polytrimethylene terephthalateresin, and 1 to 70 parts by weight of flame retardants, wherein saidflame retardants consist of 3 to 75 parts by weight of said at least one(B-1) phosphorus-containing flame retardant and 25 to 97 parts by weightof said at least one (B-2) nitrogen-containing flame retardant, withrespect to the total amount of said flame retardants.
 5. The flameretardant polytrimethylene terephthalate resin composition in accordancewith claim 1, comprising: 30 to 98 parts by weight of said (A)polytrimethylene terephthalate resin, 1 to 25 parts by weight of atleast one of said (B-1) phosphorus-containing flame retardant, and 1 to45 parts by weight of at least one of said (B-2) nitrogen-containingflame retardant.
 6. The flame retardant polytrimethylene terephthalateresin composition in accordance with claim 1, further comprising 5 to150 parts by weight of (C) an inorganic filler with respect to the totalof 100 parts by weight of 30 to 99 parts by weight of said (A)polytrimethylene terephthalate resin and 1 to 70 parts by weight of saidflame retardants comprising at least one of said (B-1)phosphorus-containing flame retardant and at least one of said (B-2)nitrogen-containing flame retardant.
 7. The flame retardantpolytrimethylene terephthalate resin composition in accordance withclaim 6, wherein said (C) inorganic filler is glass fiber.
 8. A moldingcomprising the flame retardant polytrimethylene terephthalate resincomposition in accordance with any one of claims 1, 2, 3, 4, 5, 6 and 7.9. The molding in accordance with claim 8, which is an injection moldedproduct.